#include<stdio.h>
int main()
{
{
    int low,up;
    scanf("%d %d", &low, &up);
    if(low > up)
        printf("Invalid Input");
    return 0;
}
int sum = 0;
    for (i = low; i <= up; i++)
    {
        if(i % 7 == 0)
        {
            sum += i;
        }
    }    
        printf("%d",sum);
        return 0;
}